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84 lines
2.7 KiB
Go
84 lines
2.7 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Copyright 2012 The Gorilla Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Copyright 2021 MinIO, Inc. All rights reserved.
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// forked from https://github.com/gorilla/rpc/v2
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// modified to be used with MinIO under GNU Affero General
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// Public License 3.0 license that can be found in
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// the LICENSE file.
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/*
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Package rpc is a foundation for RPC over HTTP services, providing
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access to the exported methods of an object through HTTP requests.
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This package derives from the standard net/rpc package but uses a single HTTP
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request per call instead of persistent connections. Other differences
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compared to net/rpc:
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- Multiple codecs can be registered in the same server.
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- A codec is chosen based on the "Content-Type" header from the request.
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- Service methods also receive http.Request as parameter.
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- This package can be used on Google App Engine.
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Let's setup a server and register a codec and service:
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import (
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"http"
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"github.com/minio/minio/pkg/rpc/"
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"github.com/minio/minio/pkg/rpc/json2"
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)
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func init() {
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s := rpc.NewServer()
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s.RegisterCodec(json2.NewCodec(), "application/json")
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s.RegisterService(new(HelloService), "")
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http.Handle("/rpc", s)
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}
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This server handles requests to the "/rpc" path using a JSON codec.
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A codec is tied to a content type. In the example above, the JSON codec is
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registered to serve requests with "application/json" as the value for the
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"Content-Type" header. If the header includes a charset definition, it is
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ignored; only the media-type part is taken into account.
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A service can be registered using a name. If the name is empty, like in the
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example above, it will be inferred from the service type.
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That's all about the server setup. Now let's define a simple service:
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type HelloArgs struct {
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Who string
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}
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type HelloReply struct {
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Message string
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}
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type HelloService struct {}
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func (h *HelloService) Say(r *http.Request, args *HelloArgs, reply *HelloReply) error {
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reply.Message = "Hello, " + args.Who + "!"
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return nil
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}
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The example above defines a service with a method "HelloService.Say" and
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the arguments and reply related to that method.
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The service must be exported (begin with an upper case letter) or local
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(defined in the package registering the service).
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When a service is registered, the server inspects the service methods
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and make available the ones that follow these rules:
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- The method name is exported.
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- The method has three arguments: *http.Request, *args, *reply.
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- All three arguments are pointers.
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- The second and third arguments are exported or local.
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- The method has return type error.
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All other methods are ignored.
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*/
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package rpc
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